According to a report published in the April 2004 Journal of the American Medical Association, it is estimated that one in five adults, or approximately 44 million people in the United States suffers from mild obstructive sleep apnea (OSA) and that approximately 15 million people in the United States suffer from moderate or more severe OSA. In a separate report, the American Association of Orthodontists estimates that 55 million people in the United States suffer from habitual or socially disruptive snoring.
Obstructive sleep apnea is caused by the closing of the upper airway while a person is asleep. The uvula and soft pallet collapses on the back wall of the upper airway. Then the tongue falls backward, collapsing on the back wall of the upper airway, the uvula and soft pallet forming a tight blockage, preventing any air from entering the lungs. The effort of the diaphragm, the chest and the abdomen only cause the blockage to seal tighter. In order to breathe, the person must arouse or awaken. This creates tension in the tongue thereby opening the airway, allowing air to pass into the lungs.
Obstructive sleep apnea causes a drop in a person's blood oxygen saturation (SaO2) and an increase in the blood's carbon dioxide (CO2). When the SaO2 drops the heart will start pumping more blood with each beat. If the SaO2 continues to drop the heart will start beating faster and faster. As the CO2 increases the brain will try to drive the person to breathe. The effort and action of the abdomen and chest will increase. Eventually that action will clear the upper airway blockage, allowing the person to breathe. A cyclic process of arousal and falling back to sleep will typically occur throughout the person's sleep.
The American Academy of Sleep Medicine rates the average number of OSA events per hour as your Respiratory Distress Index (RDI). An RDI of 0 to 5 is normal; 5 to 20 is mild; 20 to 40 is moderate; over 40 is considered severe. An apnea event must last at least 10 seconds to be considered an event. It is not uncommon to see RDIs well above the 40. In some cases RDIs were well above 100, with events lasting as long as 90 to 120 seconds and SaO2s going below 70% when normal is 95% to 100%.
Obstructive sleep apnea is a serious, potentially life-threatening condition that is far more common than generally understood. Recent studies have linked OSA with increased risks of cardiovascular morbidity, high blood pressure, stroke, heart attack, Type II diabetes and depression. OSA typically causes excessive daytime sleepiness, resulting in memory loss, lack of concentration, slower reaction time that can cause difficulty driving or operating equipment and sexual dysfunction, such as impotence and libido.
There are several methods, devices and surgical procedures presently available for the treatment of OSA. The most frequently prescribed and most common treatment is continuous positive airway pressure, or CPAP. CPAP therapy requires that the patient wear a nasal or facial mask during sleep that is connected by a tube to a portable airflow generator, which delivers air at a predetermined continuous positive pressure. The continuous positive pressure forces air through the nasal passages and opens the back of the throat, keeping the upper airway open and unobstructed during sleep. CPAP prevents upper airway closure while in use, but apnea or hypopnea episodes return when CPAP is stopped or used improperly. CPAP is not a cure for OSA, but a lifelong therapy for managing OSA that must be used on a nightly basis. Noncompliance rates for CPAP are estimated to exceed 50% due to factors such as physical discomfort and claustrophobia resulting from use of the nasal or facial mask, nasal and facial irritation, uncomfortable sleeping positions, lifestyle changes, social factors and inconvenience.
Another mechanical therapy prescribed to treat OSA is a custom fitted or prefabricated orthodontic like device or oral appliance that is worn while sleeping. An oral appliance attempts to reposition the jaw and/or the base of the tongue to prevent the tongue from collapsing and obstructing the upper airway during sleep.
When surgical therapy is indicated, conservative procedures are attempted first. These procedures include uvulectomy, nasal reconstruction, Aden tonsillectomy, uvulopalatopharyngoplasty (UPPP or UP3) and laser assisted uvulopalatoplasty (LAUP). Second line treatments for OSA are more complex and include genioglossal advancement with or without hyoid myotomy, maxillary mandibular advancement, bimaxillary advancement, and tongue base surgery. The more invasive of these surgical procedures are very painful, usually require post procedure prescription narcotics to manage pain, often result in potentially serious post surgical complications which can involve hospital readmission, usually result in lengthy recovery periods and are expensive to administer.
Uvulopalatopharyngoplasty, currently the most common palatal surgical treatment for both OSA and snoring, uses a scalpel, electrocautery, coblation or other cutting technology to remove excess tissue at the back of the throat (tonsils, uvula, and part of the soft palate) under general anesthesia. The UPPP procedure is very painful, often requires an overnight hospital stay, sometimes requires hospital readmission to resolve complications, and typically involves lengthy recovery period of up to two weeks. Surgical success rate is approximately 50% when surgical success is defined as both 50% reduction in RDI and a postoperative RDI of less than 20. This is despite preselection of patients where the uvula and soft palate are identified as the cause of OSA.
Laser assisted uvulopalatoplasty is similar to UPPP, but uses heat from a laser to destroy tissue of the soft palate. The LAUP procedure requires the use of expensive laser capital equipment and often involves multiple treatments. The clinical and economic benefits of using LAUP over UPPP have not been well established and as a result, LAUP procedures are now performed infrequently.
A vast majority of people with OSA have tongue base narrowing or posterior displacement of the tongue into the airway. Several highly invasive surgical procedures with concomitant high morbidity but significantly improved clinical results compared to UPPP and LAUP have been used to address this issue. Genioglossal (primary muscle of the tongue) advancement involves performing a mandibular osteotomy (reconstruction of the lower jaw) with anterior repositioning of the genioglossus attached segment of the mandible, which results in anterior displacement of the tongue. This procedure is painful and requires long recovery and sometimes results in permanent numbness of the lower front teeth.
Maxillomandibular advancement is the most invasive and effective surgical treatment for OSA. The procedure involves moving both the maxilla (upper jaw) and the mandible forward to establish an open airway. Success rates of 90% to 100% with maxillomandibular advancement surgery as the primary procedure have been reported. While speech and swallowing are typically not affected, this procedure is painful, requires a long recovery and sometimes it causes numbness of the lower lip and some changes in facial appearance. Chewing is not allowed for 4 weeks and typically, patients will not return to work in less than one month post procedure.